U.S. patent number 5,755,986 [Application Number 08/717,538] was granted by the patent office on 1998-05-26 for soft-magnetic dielectric high-frequency composite material and method for making the same.
This patent grant is currently assigned to Alps Electric Co., Ltd.. Invention is credited to Takashi Hatanai, Teruyoshi Kubokawa, Akihiro Makino, Takao Mizushima, Yutaka Yamamoto.
United States Patent |
5,755,986 |
Yamamoto , et al. |
May 26, 1998 |
**Please see images for:
( Certificate of Correction ) ** |
Soft-magnetic dielectric high-frequency composite material and
method for making the same
Abstract
A high-frequency composite material, having soft magnetic and
dielectric characteristics, comprising a soft magnetic alloy powder
represented by the general composition A.sub.a M.sub.b D.sub.c and
a synthetic resin, wherein A represents at least one element or
mixture thereof selected from the group consisting of Fe, Co and
Ni; M represents at least one element or mixture thereof selected
from the group consisting of Hf, Zr, W, Ti, V, Nb, Mo, Cr, Mg, Mn,
Al, Si, Ca, Sr, Ba, Cu, Ga, Ge, As, Se, Zn, Cd, In, Sn, Sb, Te, Pb,
Bi and rare earth elements; D represents at least one element or
mixture thereof selected from the group consisting of O, C, N and
B; and the suffixes a, b, and c in the general formula A.sub.a
M.sub.b D.sub.c satisfy the following equations represented by
atomic percent: 40.ltoreq.a<80, 0.ltoreq.b.ltoreq.30, and
0<c.ltoreq.50.
Inventors: |
Yamamoto; Yutaka (Niigata-ken,
JP), Mizushima; Takao (Niigata-ken, JP),
Makino; Akihiro (Niigata-ken, JP), Hatanai;
Takashi (Niigata-ken, JP), Kubokawa; Teruyoshi
(Fukushima-ken, JP) |
Assignee: |
Alps Electric Co., Ltd. (Tokyo,
JP)
|
Family
ID: |
17149565 |
Appl.
No.: |
08/717,538 |
Filed: |
September 19, 1996 |
Foreign Application Priority Data
|
|
|
|
|
Sep 25, 1995 [JP] |
|
|
7-246516 |
|
Current U.S.
Class: |
252/62.54;
148/100; 148/101; 148/102; 252/62.55 |
Current CPC
Class: |
C22C
1/0441 (20130101); H01F 1/37 (20130101) |
Current International
Class: |
C22C
1/04 (20060101); H01F 1/37 (20060101); H01F
1/12 (20060101); H01F 001/28 (); H01F 001/24 ();
H01F 001/147 () |
Field of
Search: |
;252/62.54,62.55
;148/100,101,102 |
References Cited
[Referenced By]
U.S. Patent Documents
|
|
|
4689163 |
August 1987 |
Yamashita et al. |
4985089 |
January 1991 |
Yoshizawa et al. |
5051200 |
September 1991 |
Srail et al. |
5129963 |
July 1992 |
Panchanathan et al. |
|
Foreign Patent Documents
Primary Examiner: Bonner; Melissa
Attorney, Agent or Firm: Shoup; Guy W.
Claims
What is claimed is:
1. A high-frequency composite material, having soft magnetic and
dielectric characteristics, comprising a soft magnetic alloy powder
represented by the general composition A.sub.a M.sub.b D.sub.c and
a synthetic resin,
wherein A represents at least one element or mixture thereof
selected from the group consisting of Fe, Co and Ni, M represents
at least one element or mixture thereof selected from the group
consisting of Hf, Zr, W, Ti, V, Nb, Mo, Cr, Mg, Mn, Al, Si, Ca, Sr,
Ba, Cu, Ga, Ge, As, Se, Zn, Cd, In,Sn, Sb, Te, Pb, Bi, and rare
earth elements, and D represents at least one element or mixture
thereof selected from the group consisting of O, C and N,
wherein the suffixes a, b, and c in said general formula A.sub.a
M.sub.b D.sub.c satisfy the following equations represented by
atomic percent:
40<a<80,
0<b<30, and
0<c<50, and
wherein soft magnetic alloy powder comprises agglomerates having an
average particle size of 1 to 2 .mu.m, where each agglomerate
includes A in the form of body centered cubic (bcc) fine
crystalline grains having an average grain size of a few nm to a
few dozen nm, wherein the (bcc) fine crystalline phase is
surrounded by an amorphous phase comprising M and D which occupies
50% or more of said agglomerates.
2. A high-frequency composite material according to claim 1,
wherein an insulation layer is formed on the surface of said soft
magnetic alloy powder.
3. A method for making a high-frequency composite material having
soft magnetic and dielectric characteristics comprising:
forming a soft magnetic alloy powder having a general formula
A.sub.a M.sub.b D.sub.c by a mechanical alloying process comprising
mixing by grinding and stirring a powder A selected from the simple
substance, oxide, carbide, carbonate, nitride and boride of at
least one element selected from the group consisting of Fe, Co, and
Ni, and a powder M selected from the simple substance, oxide,
carbide, carbonate, nitride and boride of at least one element
selected from the group consisting of Hf, Zr, W, Ti, V, Nb, Mo, Cr,
Mg, Mn, Al, Si, Ca, Sr, Ba, Cu, Ga, Ge, As, Se, Zn, Cd, In, Sn, Sb,
Te, Pb, Bi and rare earth elements, in an atmosphere of a gas D
selected from the simple substance gas, oxide gas, and carbonate
gas of at least one element selected from the group consisting of
O, C and N, or of a gaseous mixture of the gas D and inert gas,
wherein the suffixes a, b and c in said general formula A.sub.a
M.sub.b D.sub.c satisfy the following equations represented by
atomic percent:
40<a<80,
0<b<30, and
0<c<50, and
wherein soft magnetic alloy powder comprises agglomerates having an
average particle size of 1 to 2 .mu.m, where each agglomerate
includes A in the form of body centered cubic (bcc) fine
crystalline grains having an average grain size of a few nm to a
few dozen nm, wherein the (bcc) fine crystalline phase is
surrounded by an amorphous phase comprising M and D which occupies
50% or more of said agglomerates;
dispersing to mix the soft magnetic alloy powder into a synthetic
resin; and
molding the mixture into the high-frequency composite material.
4. A method for making a high-frequency composite material having
soft magnetic and dielectric characteristics comprising:
forming a soft magnetic alloy powder having a general formula
A.sub.a M.sub.b D.sub.c by grinding powder of an A--M alloy ribbon,
obtained by a liquid quenching method in an atmosphere of a gas D
selected from the simple substance gas, oxide gas, and carbonate
gas of at least one element selected from the group consisting of
O, C and N, or of a gaseous mixture of the gas D and inert gas,
wherein the suffixes a, b, and c in said general formula A M.sub.b
D.sub.c satisfy the following equations represented by atomic
percent:
40<a<80,
0<b<30, and
0<c<50, and
wherein soft magnetic alloy powder comprises agglomerates having an
average particle size of 1 to 2 .mu.m, where each agglomerate
includes A in the form of body centered cubic (bcc) fine
crystalline grains having an average grain size of a few nm to a
few dozen nm, wherein the (bcc) fine crystalline phase is
surrounded by an amorphous phase comprising M and D which occupies
50% or more of said agglomerates;
dispersing to mix the soft magnetic alloy powder into a synthetic
resin; and
molding the mixture into the high-frequency composite material.
5. A method for making a high-frequency composite material
according to claim 3, wherein a ground powder of an A--M alloy
ribbon obtained by a liquid quenching method is also used when said
soft magnetic alloy powder having said general formula A.sub.a
M.sub.b D.sub.c is formed by the mechanical alloying method.
6. A method for making a high-frequency composite material having
soft magnetic and dielectric characteristics comprising:
forming a soft magnetic alloy powder having the general formula
A.sub.a M.sub.b D.sub.c by a mechanical alloying process comprising
mixing by grinding and stirring a powder A selected from the simple
substance, oxide carbide, carbonate and nitride of at least one
element selected from the group consisting of Fe, Co and Ni, a
powder M selected from the simple substance, oxide, carbide,
carbonate and nitride of at least one element selected from the
group consisting of Hf, Zr, W, Ti, V, Nb, Mo, Cr, Mg, Mn, Al, Si,
Ca, Sr, Ba, Cu, Ga, Ge, As, Se, Zn, Cd, In, Sn, Sb, Te, Pb, and Bi,
and a powder D consists of C, wherein the suffixes a, b, and c in
said general formula A.sub.a M.sub.b D.sub.c satisfy the following
equations represented by atomic percent:
40<a<80,
0<b<30, and
0<c<50, and
wherein soft magnetic alloy powder comprises agglomerates having an
average particle size of 1 to 2 .mu.m, where each agglomerate
includes A in the form of body centered cubic (bcc) fine
crystalline grains having an average grain size of a few nm to a
few dozen nm, wherein the (bcc) fine crystalline phase is
surrounded by an amorphous phase comprising M and D which occupies
50% or more of said agglomerates;
dispersing to mix the soft magnetic alloy powder into a synthetic
resin; and
molding the mixture into the high-frequency composite material.
7. A method for making a high-frequency composite material having
soft magnetic and dielectric characteristics comprising:
forming a soft magnetic alloy powder having the general formula
A.sub.a M.sub.b D.sub.c by grinding powder of an A--M alloy ribbon,
obtained by a liquid quenching method in an atmosphere of a gas D
selected from the simple substance gas, oxide gas and carbonate gas
of C, wherein the suffixes a, b, and c in said general formula
A.sub.a M.sub.b D.sub.c satisfy the following equations represented
by atomic percent:
40<a<80,
0<b<30, and
0<c<50, and
wherein soft magnetic alloy powder comprises agglomerates having an
average particle size of 1 to 2 .mu.m, where each agglomerate
includes A in the form of body centered cubic (bcc) fine
crystalline grains having an average grain size of a few nm to a
few dozen nm, wherein the (bcc) fine crystalline phase is
surrounded by an amorphous phase comprising M and D which occupies
50% or more of said agglomerates;
dispersing to mix the soft magnetic alloy powder into a synthetic
resin;
and molding the mixture into the high-frequency composite
material.
8. A method for making a high-frequency composite material
according to claim 6, wherein a ground powder of an A--M alloy
ribbon obtained by a liquid quenching method is also used when said
soft magnetic alloy powder having said general formula A.sub.a
M.sub.b D.sub.c is formed by the mechanical alloying method.
9. A method for making a high-frequency composite material
according to claim 6, wherein said soft magnetic alloy powder
having the general formula A.sub.a M.sub.b D.sub.c is formed by the
mechanical alloying process in an atmosphere of a gas D selected
from the simple substance gas, oxide gas and carbonate gas of at
least one element selected from the group consisting of O, C and N,
or of a gaseous mixture of the gas D and inert gas.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates a high-frequency composite material
having both soft magnetic and dielectric characteristics and a
method for making the same, which is preferably used in applied
magnetic fields, such as antennas for liquid crystal (hereinafter
LC) televisions, magnetic head cores, magnetic cores of pulse
motors and choke coils, and transformers.
2. Description of the Related Art
Recently, the inductor in power transformers and the like has
tended toward a higher driving frequency to satisfy demands on the
miniaturization and higher performance of electronic devices. In
response to such demands, magnetic materials having higher specific
resistance, as well as soft magnetism, have been required.
Present inventors have found alloys exhibiting a high specific
resistance and excellent magnetic characteristics, such as an
Fe--Hf--O or Fe--Ta--O alloy in which Fe-base crystal and Hf or Ta
amorphous are present together, and an Fe.sub.a M.sub.b O.sub.c
alloy disclosed in U.S. patent application Ser. No. 08/201,831,
wherein M represents at least one rare earth element and a mixture
of rare earth elements. Because these soft magnetic alloys are,
however, obtained as thin films by sputtering, rod objects, such as
LC television antennas, magnetic head cores, and magnetic cores of
pulse motors are not readily available from the alloys.
In Ni ferrite, which has been used at the highest frequency among
conventional magnetic materials, Q exhibiting loss characteristics
of the core material rapidly decreases at a frequency exceeding 150
MHz, so the magnetic core loss increases. In magnetoplumpite-type
ferrite which has been developed for high-frequency magnetic
materials, Q=1 at 1 GHz, and thus the loss is unsatisfactory at a
high-frequency region of a few hundred MHz where Q is the
reciprocal of the loss coefficient (tan.delta.) and a material
exhibiting a larger Q represents a more excellent high-frequency
characteristics.
Additionally, the magnetic material must be provided with
dielectric characteristics when using a frequency exceeding a few
hundred MHz.
The present inventors have attempted to disperse by mixing alloy
powder having excellent soft magnetic characteristics into a
synthetic resin having a small dielectric loss and then to form the
mixture into a desirable shape in consideration of the application
to LC television antennas, magnetic head cores, and magnetic cores
of pulse motors.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve the
above-mentioned drawbacks, and to provide a high-frequency
composite material having both excellent soft magnetism and low
dielectric characteristics at a high frequency and being capable of
readily forming a desired shape, and a method for making the
same.
A high-frequency composite material having soft magnetic and
dielectric characteristics in accordance with the present invention
comprises a soft magnetic alloy powder represented by the general
composition A.sub.a M.sub.b D.sub.c and a synthetic resin, wherein
A represents at least one element or mixture thereof selected from
the group consisting of Fe, Co and Ni, M represents at least one
element or mixture thereof selected from the group consisting of
Hf, Zr, W, Ti, V, Nb, Mo, Cr, Mg, Mn, Al, Si, Ca, Sr, Ba, Cu, Ga,
Ge, As, Se, Zn, Cd, In, Sn, Sb, Te, Pb, Bi and rare earth elements,
and D represents at least one element or mixture thereof selected
from the group consisting of O, C, N and B.
Preferably, in the soft magnetic alloy powder having the general
formula A.sub.a M.sub.b D.sub.c in accordance with the present
invention, the suffixes a, b, and c in the general formula satisfy
the following equations represented by atomic percent:
40.ltoreq.a.ltoreq.80,
0.ltoreq.b.ltoreq.30, and
0<c.ltoreq.50.
A method for making a high-frequency composite material having soft
magnetic and dielectric characteristics in accordance with the
present invention comprises: forming a soft magnetic alloy powder
having the general formula A.sub.a M.sub.b D.sub.c set forth above
by a mechanical alloying process comprising mixing by grinding and
stirring a powder A selected from the simple substance, oxide,
carbide, carbonate, nitride and boride of at least one element
selected from the group consisting of Fe, Co and Ni, and a powder M
selected from the simple substance, oxide, carbide, carbonate,
nitride and boride of at least one element selected from the group
consisting of Hf, Zr, W, Ti, V, Nb, Mo, Cr, Mg, Mn, Al, Si, Ca, Sr,
Ba, Cu, Ga, Ge, As, Se, Zn, Cd, In, Sn, Sb, Te, Pb, Bi and rare
earth elements, in an atmosphere of a gas D selected from the
simple substance gas, oxide gas and carbonate gas of at least one
element selected from the group consisting of O, C and N, or of a
gaseous mixture of the gas D and inert gas; dispersing to mix the
soft magnetic alloy powder into a synthetic resin; and molding the
mixture into the high-frequency composite material.
Another method for making a high-frequency composite material
having soft magnetic and dielectric characteristics in accordance
with the present invention comprises: forming a soft magnetic alloy
powder having the general formula A.sub.a M.sub.b D.sub.c set forth
above by a mechanical alloying process comprising mixing by
grinding and stirring a powder A selected from the simple
substance, oxide, carbide, carbonate and nitride of at least one
element selected from the group consisting of Fe, Co and Ni, a
powder M selected from the simple substance, oxide, carbide,
carbonate and nitride of at least one element selected from the
group consisting of Hf, Zr, W, Ti, V, Nb, Mo, Cr, Mg, Mn, Al, Si,
Ca, Sr, Ba, Cu, Ga, Ge, As, Se, Zn, Cd, In, Sn, Sb, Te, Pb and Bi,
and a powder D comprising at least one element selected from the
group consisting of C and B; dispersing to mix the soft magnetic
alloy powder into a synthetic resin; and molding the mixture into
the high-frequency composite material.
In the method for making a high-frequency composite material set
forth above, the soft magnetic alloy powder having the general
formula A.sub.a M.sub.b D.sub.c set forth above is formed by the
mechanical alloying process, preferably in an atmosphere of a gas D
selected from the simple substance gas, oxide gas and carbonate gas
of at least one element selected from the group consisting of O, C
and N, or of a gaseous mixture of the gas D and inert gas.
In the methods set forth above, a ground powder of an A--M alloy
ribbon obtained by a liquid quenching method is used instead of the
powder A and powder M.
In addition, in the method set forth above, the ground powder of an
A--M alloy ribbon obtained by a liquid quenching method is also
used when the soft magnetic alloy powder having the general formula
A.sub.a M.sub.b D.sub.c is formed by the mechanical alloying
method.
Further, in the method set forth above, an insulation layer is
formed on the surface of the soft magnetic alloy powder having the
general formula A.sub.a M.sub.b D.sub.c by annealing the soft
magnetic alloy powder in an atmosphere selected from air, oxygen,
nitrogen, water vapor and their mixture, before dispersing to mix
the powder into the synthetic resin.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an electron microscopic photograph illustrating the
particle structure of the Fe.sub.a Zr.sub.b O.sub.c powder obtained
in Example 1;
FIG. 2 is an electron microscopic photograph illustrating the
surface structure of the composite material particles comprising
Fe--Zr--O and a polystyrene resin obtained in Example 1;
FIG. 3 is a graph illustrating the dielectric constant (.epsilon.)
as a function of the frequency;
FIG. 4 is a graph illustrating the value of Q (Q.epsilon.) of
dielectric members as a function of the frequency;
FIG. 5 is a graph illustrating the permeability (.mu.) as a
function of the frequency;
FIG. 6 is a graph illustrating the value of Q (Q.mu.) of dielectric
members as a function of the frequency;
FIG. 7 is a ternary diagram illustrating the value of .mu.' at 100
MHz and at room temperature as a function of the composition of the
alloy powder having a general formula of Fe.sub.a Zr.sub.b O.sub.c
in each Fe--Zr--O-silicone resin composite material and Fe-silicone
resin composite material;
FIG. 8 is a ternary diagram illustrating the value of Q.mu. at 100
MHz and at room temperature as a function of the composition of the
alloy powder having a general formula of Fe.sub.a Zr.sub.b O.sub.c
in each Fe--Zr--O-silicone resin composite material and Fe-silicone
resin composite material;
FIG. 9 is a ternary diagram illustrating the value of .mu.' at 500
MHz and at room temperature as a function of the composition of the
alloy powder having a general formula of Fe.sub.a Zr.sub.b O.sub.c
in each Fe--Zr--O-silicone resin composite material and Fe-silicone
resin composite material;
FIG. 10 is a ternary diagram illustrating the value of Q.mu. at 500
MHz and at room temperature as a function of the composition of the
alloy powder having a general formula of Fe.sub.a Zr.sub.b O.sub.c
in each Fe--Zr--O-silicone resin composite material and Fe-silicone
resin composite material;
FIG. 11 is a ternary diagram illustrating the value of Q.mu. at 1
GHz and at room temperature as a function of the composition of the
alloy powder having a general formula of Fe.sub.a Zr.sub.b O.sub.c
in each Fe--Zr--O-silicone resin composite material and Fe-silicone
resin composite material;
FIG. 12 is a ternary diagram illustrating the value of Q.mu. at 1
GHz and at room temperature as a function of the composition of the
alloy powder having a general formula of Fe.sub.a W.sub.b O.sub.c
in each Fe--W--O-silicone resin composite material;
FIG. 13 is a graph illustrating the results of X-ray diffractometry
of Fe.sub.55 Zr.sub.20 O.sub.25 alloy powder in Example 3 and
Fe.sub.60 Zr.sub.5 O.sub.35 alloy powder in Example 4; and
FIG. 14 is a graph illustrating the results of X-ray diffractometry
of Fe--Hf--O alloy powders obtained in Examples 5 to 9.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A first embodiment of a method for making a high-frequency
composite material having soft magnetic and dielectric
characteristics in accordance with the present invention will be
explained below.
First, each raw material is weighed in response to the composition
of the soft magnetic alloy powder having the general formula
A.sub.a M.sub.b D.sub.c. As raw materials, the powder A and powder
M are used.
The powder A includes powders selected from the simple substance,
oxide, carbide, carbonate, nitride and boride of at least one
element selected from the group consisting of Fe, Co and Ni. The
powder M includes powders selected from the simple substance,
oxide, carbide, carbonate, nitride and boride of at least one
element selected from the group consisting of Hf, Zr, W, Ti, V, Nb,
Mo, Cr, Mg, Mn, Al, Si, Ca, Sr, Ba, Cu, Ga, Ge, As, Se, Zn, Cd, In,
Sn, Sb, Te, Pb, Bi and rare earth elements. The rare earth elements
include at least one element selected from the group consisting of
Group 3A elements in the Periodic Table, such as Sc and Y, and
lanthanoid elements, such as La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb,
Dy, Ho, Er, Tm, Yb and Lu, and a mixture thereof. The size of each
powder grain is preferably 100 .mu.m or less for the powder A and 2
.mu.m or less for the powder M, respectively.
Next, when gaseous O, C or N is added as the component D, the
powder A and the powder M are placed into a stainless steel pot
with stainless steel balls having the same composition as the pot,
and then the pot is filled with the gas D selected from the simple
substance gas, oxide gas and carbonate gas of at least one element
selected from the group consisting of O, C and N. The contents in
the pot are ground and stirred with a high energy planetary ball
mill at a predetermined time. Such a mechanical alloying process
can form the soft magnetic alloy powder having the general formula
A.sub.a M.sub.b D.sub.c, wherein A represents at least one element
selected from the group consisting of Fe, Co and Ni, M represents
at least one element selected from the group consisting of Hf, Zr,
W, Ti, V, Nb, Mo, Cr, Mg, Mn, Al, Si, Ca, Sr, Ba, Cu, Ga, Ge, As,
Se, Zn, Cd, In, Sn, Sb, Te, Pb, Bi and rare earth elements, D
represents at least one element selected from the group consisting
of O, C, N and B, and the suffixes a, b, and c in the general
formula satisfy the following equations represented by atomic
percent: 40.ltoreq.a.ltoreq.80, 0.ltoreq.b.ltoreq.30, and
0<c.ltoreq.50.
The time for the mechanical alloying process is preferably 2 hours
or more, and more preferably 8 to 60 hours. When the time is less
than 2 hours, the (bcc) crystal of the powder A cannot be ground
into a sufficiently fine state.
In this embodiment, grinding and stirring are carried out in an
atmosphere of the gas D, and the oxygen, carbon and nitrogen
contents in the material can be controlled by using a gaseous
mixture of the gas D and an inert gas, such as Ar. Additionally,
any grinder, such as a rotor speed mill, may be used instead of the
planetary ball mill.
The resulting soft magnetic alloy powder comprises agglomerates
having an average particle size of 1 to 2 .mu.m, in which each
(bcc) fine crystalline phase A having an average crystalline grain
size of a few nm to a few dozen nm is surrounded with an amorphous
phase containing M and D in a large amount. The amorphous phase
preferably occupies 50% or more of the texture. Because the (bcc)
crystalline grain A as a constituent of the agglomerate is fine,
the alloy powder exhibits excellent soft magnetism. Further,
because the (bcc) crystalline grain A is surrounded with the high
resistance amorphous phase, eddy current loss can be
suppressed.
The element A is the primary component for imparting magnetic
characteristics to the soft magnetic alloy powder having the
general formula set forth above. Although a higher A content is
preferable to obtain a higher saturation magnetic flux density, the
specific resistance decreases at an A content of 80 atomic % or
more, and thus the permeability and Q value are deteriorated at a
high-frequency region. Whereas, the saturation magnetic flux
density decreases at an A content of 40 atomic % or less. More
preferably, the A content ranges from 45 atomic % to 70 atomic
%.
The element M is useful to achieve the objective effects set forth
above, but an M content of 30 atomic % or more causes the
deterioration in magnetic characteristics. To secure the effects
set forth above, the M content more preferably ranges from 5 atomic
% to 20 atomic %.
The element D is also useful to achieve the objective effects set
forth above, but a D content of 50 atomic % or more causes the
deterioration in magnetic characteristics, like the element M. To
secure the effects set forth above, the D content more preferably
ranges from 15 atomic % to 45 atomic %.
Next, the soft magnetic alloy powder is dispersed into a synthetic
resin solution in an organic solvent to form a slurry, and then the
slurry is repeatedly passed through a three-roll mill until the
slurry is converted to powder. The synthetic resin used in the
present invention is of low dielectric loss, for example,
polypropylene, polyethylene, polystyrene, paraffine,
polytetrafluoroethylene, polycarbonate, and silicone resins. The
organic solvents for dissolving the synthetic resin may include
xylene, toluene, and benzene.
The amount of the soft magnetic alloy powder added to the synthetic
resin can be adequately determined in response to magnetic and
dielectric characteristics of the targeted composite material. The
content of the soft magnetic alloy powder is preferably 50 to 80
volume % of the slurry. When the content of the soft magnetic alloy
powder is less than 50 volume %, the permeability may decrease,
whereas when a content exceeding 80 volume % may cause difficulty
in a molding process, such as injection molding.
Preferably, the soft magnetic alloy powder is annealed in an
atmosphere selected from air, oxygen, nitrogen, and water vapor,
and a mixture thereof, before dispersing into and mixing with the
synthetic resin solution. The annealing is carried out preferably
at 25.degree. to 300.degree. C. for 0.5 to 48 hours. By annealing,
an oxide insulation layer is formed on the surface of the soft
magnetic alloy powder, so that the specific resistance of the
powder increases to lower the dielectric constant at a
high-frequency. Any insulation layer other than oxide film also may
be formed.
After, the organic solvent is removed from the mixture by heating
in a drying machine, the mixture is molded into a desired article
by press or compression molding, injection molding, extrusion, or
the like. The molding is heated at 150.degree. to 400.degree. C.
for approximately one hour to endow the high-frequency composite
material with the soft magnetic and dielectric characteristics.
Next, a second embodiment of a method for making a high-frequency
composite material having soft magnetic and dielectric
characteristics in accordance with the present invention will be
explained below.
The second method differs from the first method in that after the
powder A, the powder M and the powder D are mixed the mixture is
ground and stirred in an atmosphere of an inert gas or of a gas D
selected from the simple substance gas, oxide gas, carbonate gas of
at least one element selected from the group consisting of O, C and
N, in the second method, whereas after the powder A and the powder
B is mixed the mixture is ground and stirred in an atmosphere of
the gas D in the first method.
Examples of the powder D include at least one element selected from
the group consisting of C and B.
The grinding and stirring of the powder A, the powder M, and the
powder D is carried out in an atmosphere of the gas D, of an inert
gas, e.g. Ar, or of a gaseous mixture of the gas D and inert gas.
When the gaseous mixture is used, the oxygen, carbon and nitrogen
content in the material can be controlled.
The high-frequency composite material having soft magnetic and
dielectric characteristics can be produced by the second
method.
A third embodiment of a method for making a high-frequency
composite material having soft magnetic and dielectric
characteristics in accordance with the present invention will be
explained below.
The third method differs from the first and second methods in that
a ground powder of an A--M alloy ribbon obtained by a liquid
quenching method is used instead of the powder A and the powder
B.
The A--M alloy ribbon can be prepared by any liquid quenching
method, for example, a single roll method in which A--M molten
alloy is sprayed from a nozzle on the cooled roll surface while
rotating at a high speed; or a double roll method in which A--M
molten alloy is jetted between two rotating cooled rolls coming
into contact with each other. In the single roll method, a wide and
long ribbon having a thickness of 8 to 35 .mu.m and having
different surface roughnesses of the roll side face (coming into
contact with the roll) and the free face (not coming into contact
with the roll), since the A--M molten alloy is cooled by the
contact with the roll surface. On the other hand, in the double
roll method, a thicker ribbon having a smooth surfaces and a
uniform thickness is obtainable compared with the single roll
method, but a wide and long ribbon is barely obtainable, because
the both surfaces of the thin ribbon coming into contact with the
rolls and are cooled with pressure. The prepared A--M alloy ribbon
is ground and placed into a high energy planetary ball mill.
The high-frequency composite material having soft magnetic and
dielectric characteristics can be produced by the third method.
A fourth embodiment of a method for making a high-frequency
composite material having soft magnetic and dielectric
characteristics in accordance with the present invention will be
explained below.
The fourth method differs from the first and second methods in that
a ground powder of an A--M alloy ribbon obtained by a liquid
quenching method is used together with the powder A, the powder M,
and the powder D and/or the gas D.
The high-frequency composite material having soft magnetic and
dielectric characteristics can be produced by the fourth
method.
The composite material obtained by the method set forth above has a
specific resistance of 108 .OMEGA..multidot.cm or more, a
dielectric characteristics as an insulator (dielectric) due to the
synthetic resin, and soft magnetism due to the soft magnetic alloy
powder, at the same time. In particular, at a high-frequency region
of a few hundred MHz or more, the composite material has a high Q
value, for example, Q=30 at 1 GHz, as well as excellent magnetic
characteristics, and thus it can be used at a range from a few
hundred MHz to a GHz zone, differing from prior art magnetic
materials. Further, since the high-frequency composite material
comprises the soft magnetic alloy powder dispersed into the
synthetic resin, the material can be readily molded compared with
the sole soft magnetic alloy powder.
The high-frequency composite material in accordance with the
present invention can be readily molded into a desirable shape,
e.g. a rod, compared with prior art thin film materials, and thus
can be widely applied to magnetic parts, e.g. LC television
antennas, magnetic head cores, transformer cores, and magnetic
cores of pulse motors. Further, magnetic parts having excellent
magnetic characteristics and low dielectric loss at a
high-frequency region is obtainable from the high-frequency
composite material, and the magnetic parts can be miniaturized. For
example, when an LC television antenna is produced with the
high-frequency composite material in accordance with the present
invention, the sending/receiving level of the antenna is improved
and the more compact antenna can be produced.
EXAMPLES
The present invention will now be explained in detail based on
several examples and a comparative examples but the present
invention is not limited to these Examples.
Example 1
After 11.49 g of electrolytic iron (Toho Zinc Co., Ltd., less than
200 mesh) and 4.61 g of zirconium oxide (Daiichi-Kigenso Co., Ltd.,
less than 45 .mu.m) were weighed and placed into a 170-ml stainless
steel pot (SUS 304), oxygen gas was introduced. After 238 g of
stainless balls (diameter 4 mm) of the same materials as the pot
were placed into the pot, the content was subjected to a mechanical
alloying process. The content was mixed by grinding and stirring
using a high energy planetary ball mill (Kurimoto Limited) at a
centrifugal acceleration of 100 G, a rotation speed/revolution
speed ratio of 448 rpm/588 rpm, for 8 hours to obtain Fe.sub.a
Zr.sub.b O.sub.c alloy powder, wherein a is 55, b is 10, and c is
35. FIG. 1 is an electron microscopic photograph illustrating the
particle structure of the Fe.sub.a Zr.sub.b O.sub.c alloy
powder.
The obtained Fe.sub.a Zr.sub.b O.sub.c alloy powder was annealed in
air at 100.degree. C. for 2 hours to form an oxide insulation film
on the powder surface, a polystyrene resin in xylene solution was
added to the Fe.sub.a Zr.sub.b O.sub.c alloy powder to obtain a
slurry until the Fe.sub.a Zr.sub.b O.sub.c alloy powder content
reaches 50 volume %. The slurry was repeatedly passed through a
three-roll mill to obtain a composite powder comprising the
Fe.sub.a Zr.sub.b O.sub.c alloy powder and polystyrene resin. The
composite powder was dried in a drying machine at 80.degree. C. for
12 hours. A disk mold article was made of the dry composite powder
with a compression mold. The disk mold article was dried at
150.degree. C. for 1 hour to obtain a composite material comprising
Fe--Zr--O and a polystyrene resin and having an outer diameter of
15 mm and a thickness of 3 mm. FIG. 2 is an electron microscopic
photograph illustrating the surface structure of the composite
material particles comprising Fe--Zr--O and a polystyrene
resin.
Example 2
A composite material comprising Fe--Zr--O and a polystyrene resin
was prepared by the method identical to Example 1, except that an
insulation layer is formed by oxidizing the surface of the Fe.sub.a
Zr.sub.b O.sub.c alloy powder obtained by the mechanical alloying
process, at 120.degree. C. for 4 hours in air.
Comparative Example
Ni ferrite is used for antennas for pagers as a magnetic material
in the most high-frequency region. From Ni ferrite used in a pager
(resonance frequency: 172 MHz) made by Motorola, Inc., a
.phi.8.0-.phi.4.0-t1.5 mm ring sample and a .phi.15.0-t2.0 mm disk
sample were prepared by cutting for a comparative magnetic
material.
Test 1
The specific resistance and permeability of each composite material
obtained by Examples 1 and 2 and of the magnetic material obtained
by Comparative Example, as well as the Q values as their respective
magnetic members, were evaluated. The specific resistance is
measured by using a disk testing sample with carbon tapes on the
both faces with a super mega-ohm meter Model SM-9E by Toa
Electronics Ltd. The permeability and the Q value as the magnetic
member were measured by using a .phi.8.0-.phi.4.0-t1.5 mm ring
sample and .phi.15.0-t2.0 mm disk sample with a material analyzer
4291A by Hewlett-Packard Company at a frequency range from 1 MHz to
1.8 GHz. The results are shown in FIGS. 3 to 6.
FIG. 3 is a graph illustrating the dielectric constant (.epsilon.)
as a function of the frequency, FIG. 4 is a graph illustrating the
value of Q (Q.epsilon.) of a dielectric member as a function of the
frequency, FIG. 5 is a graph illustrating the permeability (.mu.)
as a function of the frequency, and FIG. 6 is a graph illustrating
the value of Q (Q.mu.) of a dielectric member as a function of the
frequency.
FIG. 3 evidently demonstrates that the composite material obtained
in Example 1 has dielectric characteristics similar to the magnetic
material in Comparative Example, and the composite material
obtained at a higher heating temperature and for a longer heating
time in Example 2 has a smaller dielectric constant than the
materials in Example 1 and Comparative Example.
FIG. 4 demonstrates that the composite materials in Examples 1 and
2 exhibit excellent magnetic loss characteristics, i.e., larger Qe
values than that in Comparative Example at a high-frequency region
of 800 MHz or more.
FIG. 5 demonstrates that the composite materials in Examples 1 and
2 exhibit stable permeability at a high-frequency region of 800 MHz
or more, whereas the permeability of the magnetic material in
Comparative Example decreases with the increase in the frequency.
In particular, the composite material in Example 1 exhibits a
higher permeability than that in Comparative Example at a
high-frequency region of approximately 1,500 MHz or more.
FIG. 6 demonstrates that the composite materials in Examples 1 and
2 exhibit larger Q.epsilon. values than that in Comparative Example
at a high-frequency region of 400 MHz or more.
Test 2
A series of Fe--Zr--O-silicone resin composite materials (Samples 1
to 15) were prepared by dispersing Fe.sub.a Zr.sub.b O.sub.c alloy
powders into a silicone resin, by mixing them and by forming the
mixture, of which the atomic percents were varied within follows:
from 45 to 100 atomic % for Fe, 5 to 20 atomic % for Zr, and 15 to
45 atomic % for O, similar to Example 1.
The correlation between the composition of Fe.sub.a Zr.sub.b
O.sub.c alloy powder and the .mu.' values at room temperature and
at 100 MHz and 500 MHz, and the Q.mu. values at room temperature,
and at 100 MHz, 500 MHz and 1 GHz. The results are shown in Table 1
and FIGS. 7 to 11.
TABLE 1 ______________________________________ Composition Fe Zr O
Q.mu. .mu.' Q.mu. Sample No. (at %) (at %) (at %) *1 *2 *3
______________________________________ 1 55 10 35 142.9/56.5
3.2/3.3 17.4 2 60 5 35 111.3/48.1 3.0/3.0 19.9 3 55 20 25
110.0/17.3 2.7/2.7 7.6 4 60 15 25 114.3/14.5 3.2/3.2 6.4 5 70 5 25
136.7/27.8 3.6/3.7 6.6 6 65 20 15 25.9/16.1 1.8/1.7 10.7 7 70 15 15
92.2/10.8 3.6/3.7 4.9 8 75 10 15 132.2/10.0 3.9/4.1 4.4 9 45 10 45
70.9/31.4 1.9/1.9 20.7 10 50 5 45 107.6/37.9 2.5/2.6 18.4 11 55 0
45 107.7/41.1 2.5/2.5 21.1 12 50 15 35 87.0/55.4 1.6/1.6 35.2 13
65.3 8.9 25.8 146.5/27.9 3.8/4.0 7.1 14 100 0 0 12.3/3.6 5.0/4.3
2.4 (for Com- parison)*4 15 100 0 0 2.2/1.6 3.9/2.1 1.4 (for Com-
parison)*5 ______________________________________ *1 Q.mu. at f =
100 MHz/Q.mu. at f = 500 MHz *2 .mu.' at f = 100 MHz/.mu.' at f =
500 MHz *3 Q.mu. at f = 1 GHz *4 MA *5 Nonelectrolytic iron
FIG. 7 is a ternary diagram illustrating the .mu.' value at 100 MHz
and at room temperature as a function of the composition of the
alloy powder having a general formula of Fe.sub.a Zr.sub.b O.sub.c
in each Fe--Zr--O-silicone resin composite material and Fe-silicone
resin composite material, in which the .mu.' value is shown above
each point representing the composition of the respective alloy
powder.
FIG. 8 is a ternary diagram illustrating the value of Q.mu. at 100
MHz and at room temperature as a function of the composition of the
alloy powder having a general formula of Fe.sub.a Zr.sub.b O.sub.c
in each Fe--Zr--O-silicone resin composite material and Fe-silicone
resin composite material, in which the Q.mu. value is shown above
each point representing the composition of the respective alloy
powder.
FIG. 9 is a ternary diagram illustrating the value of .mu.' at 500
MHz and at room temperature as a function of the composition of the
alloy powder having a general formula of Fe.sub.a Zr.sub.b O.sub.c
in each Fe--Zr--O-silicone resin composite material and Fe-silicone
resin composite material, in which the .mu.' value is shown above
each point representing the composition of the respective alloy
powder.
FIG. 10 is a ternary diagram illustrating the value of Q.mu. at 500
MHz and at room temperature as a function of the composition of the
alloy powder having a general formula of Fe.sub.a Zr.sub.b O.sub.c
in each Fe--Zr--O-silicone resin composite material and Fe-silicone
resin composite material, in which the Q.mu. value is shown above
each point representing the composition of the respective alloy
powder.
FIG. 11 is a ternary diagram illustrating the value of Q.mu. at 1
GHz and at room temperature as a function of the composition of the
alloy powder having a general formula of Fe.sub.a Zr.sub.b O.sub.c
in each Fe--Zr--O-silicone resin composite material and Fe-silicone
resin composite material, in which the Q.mu. value is shown above
each point representing the composition of the respective alloy
powder.
Table 1 and FIGS. 7 to 11 evidently demonstrate that each
Fe--Zr--O-silicone resin composite material in Samples 1 to 13 as
Examples in accordance with the present invention has a higher
Q.mu. value than those in Samples 14 and 15 for comparison at 100
MHz, 500 MHz and 1 GHz. In particular, each composite material
containing 45 to 70 atomic percent of Fe, 0 to 20 atomic percent of
Zr, and 15 to 45 atomic percent of O has a Q.mu. value higher than
4 at a 1 GHz, and the material in Sample 12 has an extremely high
Q.mu. value, i.e., 35.2.
Test 3
A series of Fe--W--O-silicone resin composite materials (Samples 16
to 25) were prepared by dispersing Fe.sub.a W.sub.b O.sub.c alloy
powders into a silicone resin, by mixing them and by forming the
mixture, of which the atomic percents were varied within ranges as
follows: from 55 to 75 atomic % for Fe, 5 to 20 atomic % for W, and
15 to 35 atomic % for O, similar to Example 1.
The correlation between the composition of Fe.sub.a W.sub.b O.sub.c
alloy powder and the Q.mu. values at room temperature and at 1 GHz.
The results are shown in Table 2 and FIG. 12.
TABLE 2 ______________________________________ Composition Fe W O
Sample No. (at %) (at %) (at %) Q.mu.
______________________________________ 16 55 10 35 11.9 17 60 5 35
10.1 18 55 20 25 5.5 19 60 15 25 5.5 20 70 5 25 12.6 21 65 20 15
4.1 22 70 15 15 4.2 23 75 10 15 3.9 24 65.3 8.9 25.8 4.9 25 65.3
8.9 25.8 4.9 ______________________________________
FIG. 12 is a ternary diagram illustrating the value of Q.mu. at 1
GHz and at room temperature as a function of the composition of the
alloy powder having a general formula of Fe.sub.a W.sub.b O.sub.c
in each Fe--W--O-silicone resin composite material, in which the
Q.mu. value is shown above each point representing the composition
of the respective alloy powder.
Tables 1 and 2 and FIG. 12 evidently demonstrate that each
Fe--W--O-silicone resin composite material in Samples 16 to 25 as
Examples in accordance with the present invention has a higher
Q.mu. value than Fe-silicone resin composite materials in Samples
14 and 15 for comparison at 1 GHz within the range of 45 to 70
atomic percent of Fe, 0 to 20 atomic percent of Zr, and 15 to 45
atomic percent of O.
Example 3
After 9.860 g of electrolytic iron (Toho Zinc Co., Ltd., less than
200 mesh), 4.944 g of zirconium oxide (Daiichi-Kigenso Co., Ltd.,
less than 45 .mu.m) and 2.196 g of zirconium were weighed and
placed into a 170-ml stainless steel pot (SUS 304), oxygen gas was
introduced. After 238 g of stainless balls (diameter 4 mm) of the
same materials as the pot were placed into the pot, the content was
subjected to a mechanical alloying process. The content was mixed
by grinding and stirring using a high energy planetary ball mill
(Kurimoto Limited) at a centrifugal acceleration of 100 G, a
rotation speed/revolution speed ratio of 448 rpm/588 rpm, for 8
hours to obtain Fe.sub.55 Zr.sub.20 O.sub.25 alloy powder. The
result of the X-ray diffractometry of the obtained Fe.sub.55
Zr.sub.20 O.sub.25 alloy powder will be shown in FIG. 13.
Example 4
After 13.044 g of electrolytic iron (Toho Zinc Co., Ltd., less than
200 mesh) and 2.398 g of zirconium oxide (Daiichi-Kigenso Co.,
Ltd., less than 45 .mu.m) were weighed and placed into a 170-ml
stainless steel pot (SUS 304), 1.577 g of oxygen gas was
introduced. After 238 g of stainless balls (diameter 4 mm) of the
same materials as the pot were placed into the pot, the content was
subjected to a mechanical alloying process. The content was mixed
and ground with stirring using a high energy planetary ball mill
(Kurimoto Limited) at a centrifugal acceleration of 100 G, a
rotation speed/revolution speed ratio of 448 rpm/588 rpm, for 8
hours to obtain Fe.sub.60 Zr.sub.5 O.sub.35 alloy powder. The
result of the X-ray diffractometry of the obtained Fe.sub.60
Zr.sub.5 O.sub.35 alloy powder will also be shown in FIG. 13.
The Fe.sub.55 Zr.sub.20 O.sub.25 and Fe.sub.60 Zr.sub.5 O.sub.35
alloy powders in Examples 3 and 4 have X-ray diffraction patterns
similar to each other, in spite of different raw material
formulations.
Examples 5 to 9
After 7.935 g of electrolytic iron (Toho Zinc Co., Ltd., less than
200 mesh) and 9.065 g of hafnium oxide (Kojundo Chemical Laboratory
Co., Ltd., 2 .mu.m) were weighed and placed into a 170-ml stainless
steel pot (SUS 304), inert gas was introduced. Five kinds of
Fe.sub.a Hf.sub.b O.sub.c powder (a=54.9, b=11 and c=34.1) were
prepared by various mechanical alloying times, i.e., 0.5 hours, 2
hours, 8 hours, 16 hours and 60 hours. Using a high energy
planetary ball mill (Kurimoto Limited) of which the pot is filled
with 238 g of stainless balls (diameter 4 mm) of the same materials
as the pot, the content was mixed by grinding and stirring at a
centrifugal acceleration of 100 G, a rotation speed/revolution
speed ratio of 448 rpm/588 rpm.
Mechanical alloying times for obtaining Fe.sub.a Hf.sub.b O.sub.c
alloy powders in Examples 5, 6, 7, 8 and 9 were 0.5, 2, 8, 16 and
60 hours, respectively. The results of the X-ray diffractometry of
the obtained Fe--Hf--O alloy powders will also be shown in FIG. 14.
FIG. 14 evidently demonstrates that Hf and O are incorporated in Fe
and the peak intensities at the 2.theta.=55.degree. and
2.theta.=100.degree. decrease, and thus the mechanical alloying
process proceeds with the time.
Because the high-frequency composite material exhibiting soft
magnetic and dielectric characteristics in accordance with the
present invention comprises a synthetic resin having a small
dielectric loss and a soft magnetic alloy powder having the general
formula A.sub.a M.sub.b D.sub.c as set forth above, the specific
resistance of the obtained composite material is 10.sup.8
.OMEGA..multidot.cm or more, the composite material has the
dielectric characteristics as the insulator (or dielectric member)
of the synthetic resin and the soft magnetism of the soft magnetic
alloy powder. In particular, the composite material has a high Q
value, as well as excellent magnetic characteristics, at a
high-frequency region of a few hundreds MHz or more, for example,
Q=30 at 1 GHz. Thus, the composite material can be used in a few
hundreds MHz to a few GHz region in which no conventional magnetic
material is available. Further, in the high-frequency composite
material, the soft magnetic alloy powder is dispersed into the
synthetic resin, and thus a desired product can be readily formed
compared with the production from only the soft magnetic alloy
powder.
Accordingly, because a desired shape, such as a rod, can be formed
from the high-frequency composite material in accordance with the
present invention, the composite material is widely applicable to
LC television antennas, magnetic head cores, transformer cores, and
magnetic parts such as magnetic cores of pulse motors. Further, the
composite material has excellent magnetic characteristics at a
high-frequency region, can form a magnetic part having a low
dielectric loss, and enables the magnetic part to miniaturize. For
example, a compact LC television antenna with an improved
sending/receiving level can be produced from this composite
material.
The production method in accordance with the present invention is
preferably used for the production of high-frequency composite
materials having soft magnetic and dielectric characteristics, as
set forth above.
* * * * *